This invention relates to heating of nose fairings for rotating blade assemblies as for example gas turbine engine intakes, rotating ram air turbines and the like. The new heating apparatus has an electrical generator incorporated into the rotating blade assembly and the support structure thereof that provides electrical energy to a heating element mounted in the forward portion of the nose cone or fairing.
Ram air turbines (RATs) can be used in commercial aviation as emergency power systems. They typically will have a turbine with a rotating hub and a plurality of blades. The front of the turbine hub (i.e., nose cone) can be prone to ice build-up. Problems arise if the ice breaks loose, hits, and then damages any down stream aircraft features, particularly engine inlets.
There are various means for heating, for purposes of deicing, the nose fairing of a rotating hub of an airfoil blade assembly. The heating may either maintain a temperature above the freezing point of water or may be engaged when ice forms on the nose cone to deice the structure.
An example of an apparatus for heat generation in the nose cone of a ram air turbine is disclosed in U.S. Pat. Nos. 5,558,495 and 5,746,580, issued Sep. 24, 1996 and May 5, 1998 respectively. In this invention electromagnetic induction is used to create heat between two relatively rotating components. In one embodiment a rotating nose cone is formed from electrically conductive material and a relatively fixed assembly of permanent magnet pole pieces positioned to interact with the nose cone material. The relative motion of the elements causes a change in magnetic flux to create heating in the nose cone material to prevent icing or for deicing. Some disadvantages to this design include the fact that additional elements such as bearings, shafts and the like must be incorporated into the existing ram air turbine structure. These additions, particularly the added bearings and shafts, increase the shaft rotational complexity that lowers the reliability of the system.
A further example of a deicing apparatus is found in U.S. Pat. No. 5,623,821. In this instance a rather complicated microwave system is incorporated in the blade and support assembly of an air intake device. The system is designed to deice the blades and nose cone of the air intake device. This system for deicing requires the incorporation of wave guide elements and microwave generators to generate and control the use of the microwave energy. Disadvantages with this system are the requirement for a significant redesign or change in structure of many of the elements of a turbine fan or air intake system to incorporate the structure necessary to distribute the microwave energy. This is principally the need for wave guide structure. The design of such a structure incurs added complexity when related to rotating blade assemblies as with RATs.
As can be seen, there is a need for a simple efficient apparatus and method to heat the nose fairing or nose cone of rotating blade assemblies.
An improved heating apparatus for nose fairings of rotating blade assemblies according to the present invention comprises an electrical generator connected to a heating element mounted in the forward portion of the nose fairing. In the preferred embodiment the rotor element of the generator is incorporated into the rotating blade hub assembly to facilitate electrical connection to the heating element. The stator element is incorporated into the fixed support structure of the rotating blade hub assembly. The electrical energy created by the rotational energy is used to power the heating element.